AGRONOMIJAS VĒSTIS - Latvijas Lauksaimniecības universitāte

AGRONOMIJAS VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008tillage were carried out with heavy disc harrows Simba Discs 34C 4.6 together with press Simbadouble press 4.6. The tractor Case 7250 Magnum Pro was used for pulling all the equipment. Thespraying of the herbicide Secator 19 d.g. (NA-methil-iodosulfuron 12.5 g kg -1 , amidosulfuron 50 gkg -1 ) 0.3 kg ha -1 was done with 18 m Hardy sprazer across trial blocks during the tillering stage ofwinter wheat.The costs of the tillage work was calculated using financial data from the company SIADobele Agra accounting system. Calculations include variable costs (fuel, the wear a spare parts)and fixed costs (labour, depreciation). Fuel consumption was determined by fuel consumptionmeasurements which show the actual amount of fuel spent per one engine hour (l mh -2 ).There were variable weather conditions with large differences among the averages duringthe experiments. Variable costs (fuel consumption and the wear of parts) were slightly differentevery year caused by different conditions. That causes large differences in the results between thethree years because of the different impact of various factors.Autumn 2000 was long and warm with a significant amount of precipitation. Thoseconditions effected the and development of winter wheat because of high weed competitiveness. Inthe spring, the weeds were already big and the effectiveness of herbicide was low. Also highamounts of precipitations during June and July of 2001 (115 un 118 mm, SIA Dobele Agra weatherstation data) caused the additionally active growth of weeds and that factor effected theproductivity of winter wheat yield results.The investigation of the second year was established under high soil moisture, caused by ahigh amount of precipitations during the summer 2001 (309 mm, SIA Dobele Agra weather stationdata). Those conditions were not favourable for quality soil tillage work, in comparison with theprevious year. Winter wheat crop growth and development were different from the previous year.Summer 2002 was sunny and very dry (June 37 mm, July 30 mm, August 0 mm, SIA Dobele Agraweather station data). In those conditions the efficiency of the herbicides was high in variations,where traditional soil cultivation with ploughing was used.The third year experiments were established under very dry soil conditions, caused by thedry summer of 2002. There was a drought period of 60 days. Under such conditions there weredifficulties to do qualitative direct sowing. The cold winter with large differences of temperaturesnegatively effected the winter hardiness of the winter wheat. Hot temperatures in July and heavyrainfalls in August effected harvesting results.The wide variables in whether conditions gave the researchers wide experience in using ofdifferent soil tillage methods under different weather and soil conditions.Analysis of correlation and regression were used for data analyse.Results and DiscussionThe trials results the investigation showed significant differences in the costs of cultivationand sowing methods (Table 1). Expenses were 36 % lower using minimal soil tillage methods butalmost 5-fold lower using direct drilling compared to traditional tillage with soil reversing andcultivating afterwards. There were additional expenses in the amount of 23.59 LVL ha -1 ontraditional tillage and 13 LVL ha -1 on minimal tillage compared to direct sowing. Differences incosts were caused by additional fuel, labour and the depreciation of machines.Table 1 Expenses of soil tillage and sowingLVL ha -1% fromTreatment 2001 2002 2003 AverageCompared to directsowingtraditionaltillageTraditional tillage 30.84 26.16 31.51 29.50 + 23.59 100Minimal tillage 18.12 15.15 23.45 18.91 + 13.00 64.08Direct sowing 6.03 5.33 6.36 5.91 - 20.03There were also significant differences in harvesting results received from particular soilcultivations and sowing methods. Grain yields were lower in treatments with reduced soil tillage. Intreatments with minimal soil tillage the obtained yield was 95.3 % from that after traditional tillagebut using direct drilling – 87.5 % (Fig. 1).70